Many electrical loads are aligned to receive electrical power from multiple sources (i.e., from both a normal power supply and a backup power supply), such that a power failure or casualty associated with one power source does not preclude the electrical loads from operating with power from another power source. Where an electrical load is particularly vital, an automatic bus transfer switch may be installed to automatically transfer the electrical load from one power source to another power source, such as from a normal source to a standby source (e.g., a backup generator or supplemental power supply).
The ability to transfer one or more loads from a first power source to a second power source may require fast-acting transfer components that are designed to quickly open a connection between the loads and the first power source, and close a connection between the loads and the second power source, in a sufficiently short period of time to ensure that the loads remain energized in the event of a power failure or casualty associated with the first power source.
For significantly large loads, including high-voltage or high-power three-phase alternating current (AC) loads, the equipment for providing power to such loads from multiple power supplies typically includes heavy-duty conductive bus bars or contacts. Because automatic transfer switches typically require the rapid opening and closure of such assemblies in a moment's notice, the physical effects of arcing, sparking, friction or other adverse effects experienced by such transfer switches during normal operation may result in an uneven or unpredictable degradation of such assemblies over time. Moreover, where the electrical loads are intended to operate in rugged, ever-changing and unstable environments, such as those encountered aboard a maritime vessel, such a transfer switch must provide reliable means for ensuring that power is transferred from the first power source to the second power source time and time again, regardless of the extent of the wear or degradation of any of the components of the transfer switch.